Spark plug



Jan. 9, 1923. 1,441,783.

A. CHAMPION ET AL.

SPARK PLUG.

FILED SEPT.25.'1918.

W 1' TNESS:

' v @Hleri sham 4011 @1136 gem-5t INVENTORS Patented Jan. 9, 1923.

UNITED STATES PATENT OFFICE.

ALBERT CHAMPION AND ALBERT SCHMIDT, OF FLINT, MICHIGAN, ASSIGNORS T0 CHAMPION IGNITION COMPANY, OF FLINT, MICHIGAN, A CORPORATION OF MICH- ean.

SPARK rLriG.

Application filed September 25, 1918. Serial No. 255,581.

One of the objects of the invention is to devise av spark plug of simple and durable construction.

Another object of the invention is to'devise a spark plug in which the insulator may be firmly seated in the shell during assembly without liability of fracture.

Another object of the invention is to devise a spark plug in which the sealing'of the joints between the insulator and shell may be most efi'ectively made.

Another object of the invention is to devise a spark plug in which the means for clamping the insulator-within the shell will distribute the pressure thereof over the greatest possible area of the insulator in an even manner, whereby maximum strength of assembly arrangement is secured.

These and other objects will more clearly appear from the following description taken in connection with the accompanying drawings which form a part of the same.

Referring to the drawings, Figure 1 is a vertical sectional view of a preferred form of our invention. Figure 2 is a vertical sectional view a modified form of our invention. Figure 3 is a vertical sectional view ofa further modified form of our invention.

Like numerals of reference indicate similar parts throughout the views.

Referring to the drawings and particularly Fig. l, 10 is the shell of a spark plug made of any desired form on the exterior thereof and having the interior bore 11 with the flange 12 on which the insulator 13 supporting the central electrode 14.- is arranged as well known in the state of the art.

The insulator comprises the body portion 15 and the upwardly extending neck portion 16, the body portion gradually reducing to the neck portion in stepped form as at 17.

' The stepped portion of the. insulator is covered with a coating of suitable varnish, bakelite or other suitable material to form a very thin gasket, and a collar 18 of hard metal is seated upon said gasket within the bore of the shell,'the exterior periphery of the collar fitting the bore of the shell and the interior periphery of the collar conforming to the contour of the stepped portion of the insulator.

The assembly of the spark plug is completed by turning over the top flange 19 of the shell onto the collar 18, the flange pressing the collar firmly down onto the stepped portion of the insulator with an even and well distributed pressure and bearing surface, whereby the insulator is pi'operly and firmly pressed'downwardly and seated on a gasket 20 on the flange 12 of the shell.

It must be understood that the advantage of evenly distributing the pressure over a large area is of very great importance, but in addition thereto should any possible leak occur past the gasket 2Q, such leak will be of no avail as the sealed collar at the top of the shell will further efiectually prevent the passage of any gas and consequent heating of the upper portion of the plug.

It must be understood that though we have shown the collar as fastened by turning in the upper flange of the shell, any suitable means such as screwing in a second collar to a correspondingly threaded portion of the shell may be employed for the purpose.

Referring particularly to the modification shown in Fig. 2, the shell 10 is shown with the upper end thereof enlarged and threaded as at 21, and the neck of the insulator 13 is shownto be of regular curved formation as at 22. This portion of the insulator is and the collar 26 is of comparatively small cross section compared with those described,

and it must be here explained that the sizes and proportions of both the gasket and the collar may vary quite widely, always providing the essential feature is maintained, that is, the collar must be of such form and material as will not distort when the pressure of assembly is brought upon it, and thus the collar will receive the direct pressure of either a clamping means, such as the turning in of the top flange of the shell, or the pressure of a collaror other member screwed 1nto the upper endoft-he shell, and will evenly distribute such pressure through the gasket tothe insulating member, which is of ifracturable material and therefore to be carefully guarded.

It must also be understoodthat any suit-'- able material may be used in place of the gasket of varnish or other suitable material referred to, and in fact, it may readily occur that the gasket at the lower seat of the insulator may be quite sufficient for sealing purposes and the gasket at the'upper part of the insulator maybe eliminated entirely, the finished interior contour of the collar and the correspondingly finished ex-' terior contour of the insulator about the neck thereof being quite sufficient to evenly distribute the pressure thereabout without causing danger of fracture.

It will be obvious to those skilled in the art that many modifications and changes may be made' without departing from the spirit and scope of the invention,

Having now described our invention what of the enlarged central portion aforesaid of said insulator, and which collar is provided with a series of internal shoulders adapted to engage the shoulders aforesiad at the upper end of the central portion of said insulator; and a top flange integral with said shell or casing and extending inwardly and over the upper end of said annular collar'to thereby hold the same in place within said interior bore.

2. A spark plug comprising a shell, an

insulator seated in said shell and having a body portion and an upwardly extending neck portion formed at the base thereof in stepped formation, a gasket of thin flexible" material fitting on said insulator at the juncture of the body and neck portions, a collar of definite shape and corresponding to-the contour of the insulator and seating on said gasket, and means engaging said collar to seat said insulator.

In testimony whereof, we afiix our signatures.

ALBERT CHAMPION.- ALBERT SCHMIDT. 

